1. Field
One or more exemplary embodiments relate to a method, apparatus, and program for encoding an image, a method, apparatus, and program for decoding an image, and an image processing system.
2. Description of the Related Art
Techniques capable of suppressing the deterioration of an image quality while increasing encoding efficiency in applying an image encoding technique such as JPEG, MPEG2, H. 264, or HEVC. For example, when an image deteriorated due to encoding is decoded, noise of the decoded image may be reduced by applying a post filter.
A bilateral filter disclosed in C. Tomasi and R. Manduchi, “Bilateral filtering for gray and color images”, IEEE International Conference on Computer Vision (ICCV1998), pp. 839-846, January 1998 is one of nonlinear filters that are capable of reducing noise by smoothening an image while maintaining an edge. In addition, Japanese Laid-open Patent Publication No. 2009-153013 and Japanese Laid-open Patent Publication No. 2012-216888 disclose a bilateral filter.
In S. Wittmann and T. Wedi, “Post-filter SEI message for 4:4:4 coding”, JVT (Joint Video Team) of ISO/IEC MPEG & ITU-T VCEG, JVT-5030, April, 2006, an encoding side designs and transmits a coefficient of a weiner filter so that a square error between a decoding image and a source image is minimized by using the encoding side having a source image (original image) before deterioration, and a decoding side performs post filtering.
In Pamphlet of International Publication No. 2009-110160, a coefficient of a weiner filter applied as a loop filter is designed in the same manner as in S. Wittmann and T. Wedi, “Post-filter SEI message for 4:4:4 coding”, JVT (Joint Video Team) of ISO/IEC MPEG & ITU-T VCEG, JVT-5030, April, 2006, and information for adaptively switching between application and non-application of a filter is set and transmitted for each block so that a square error between a source image and a decoding image is minimized to thereby improve encoding efficiency. In PCT Japanese Translation Patent Publication No. 2007-506361, Japanese Laid-open Patent Publication No. 2003-179933, and US Patent Publication No. 2011/0243249, information generated on an encoding side is transmitted to control filtering on a decoding side, similar to Pamphlet of International Publication No. 2009-110160.